Magnetic apparatus.



G. P FINNIGAN. MAGNETIC APPARATUS.

APPLICATION FILED MAR. 26, 1914.

.1, 169,475. Patented-Jan. 25, 1916.

ll mum/[w Mia/var GEORGE 1. FINNIGAN, or "\VILTON-ON-JAMES, NEAR RICHMOND, VIRGINIA.

Specification of Letters Patent.

MAGNETIC APPARATUS.

Patented Jan. 25, 191 6.

Application filed March 26, 1914. Serial No. 827,348.

T 0 all whom it may concern:

Be it known that I, GEORGE P. FINXIGAN, a citizen of the United States, residing at Wilton-on-James, near Richmond,.Henrico county, State of Virginia, have invented certain ne and useful Improvements in Magnetic Apparatus, of which the following is or associate with the electro-magnet an aux- I iliary source of magneto-motive-force, preferabl'y a" permanent magnet, so disposed with relation to the magnetic circuitof the electro-magnet andv its armature, that upon deenergization of the electro-magnet the associated source of magneto-motive-force will exert itself upon the magnetic circuit of the electro-magnet in such manner and direction as to produce or tend to produce therein a magnetic'flux opposite to that produced by the electro-magnet itself when energized,

with the result that the residual magnetism of the electro-magnet'is so greatly reduced, or completely neutralized 'or brought to zero value, or carried through zero value, to the end that the armature will not stick to or remain in contact with the pole or poles.

Foran illustration of some of the various forms my invention may take, reference may be had to the accompanying drawing, in which:

Figure 1 is an illustration of an electromagnet which has associated with its yoke -or back armature the auxiliary source of magnetoanotive force, in this case a permanent magnet. Fig. 2 discloses an application of my invention to a'solenoid and its core. Fig. is an illustration of an electromagnet'with the auxiliary source of magneto-motive-f orce applied to the magnet poles.

Referring to Fig. '1, l. and :2 represent the windings or coils of an electro-magnet, these windings being disposed in the usual man ner' upon the cores 3 and 4: generally of soft iron or other suitable magnetizable material. These cores have the back armature or yoke 5 which in this case is provided with an air gap. 6 or any other device or means, such as restriction of cross section, for introducing considerable magnetic reluctance. The armature 7 of the electro-magnet is movable to and away from the poles of the cores 3 and 4:, as upon the pivot& The coils 1 and 2 areconnected in circuit with any suitable source of current 9, such as a battery or dynamo electric generator, and with the switch or key 10.

A permanent magnet 11 has its poles preferably in magnetic contact with the yoke 5 of the electro-magnet, the poles of the permanent magnet being preferably in alinement with the cores 3 and 4, and on opposite sides of the gap 6. The reluctance of .the path through the yoke 5, and therefore the magnetic shunting effect upon permanent magnet 11, may be adjusted by turning the brass screw 8-- which moves the magnetic pieces 6 and 6 ,.disposed on opposite sides of the gap 6, toward and away from each other. Surrounding the armature 7 may be disposed the coil or winding 12 connected in circuit with any; suitable translating device 13 such as a galvanometer or any other current measuring or indicating device, or any other device which may be actuated or controlled by current passed therethrough.

The operation is as follows: Upon closure of the switch 10 current from source 9 will traverse the coils 1 and 2 and magnetize the cores 3 and 4 in the well known manner, the connections of the coils and source of current 9 being such that the pole of the core 3 is, for example, a north pole N and the pole of the core 4 is a south pole S. Under these circumstances the north pole at of the permanent magnet 11 is disposed opposite the core 4 whileits south pole s is disposed opposite the core 3. The electromagnet being energized as stated, it attracts the armature 7 and holds it in the position shown, that is, in magnetic contact with the poles N, S, without any intervening air gap or any intervening nonmagnetic material.

The air gap 6 offers relatively great reluctance to the magneto-motive-force of the permanent magnet 11, while the magnetomotive-force of the electro-magnet is so great that notwithstanding this reluctance it causes sufficiently great j magnetic flux through-its cores and poles to powerfully hold or attract the armature T. if new the electro-magnet be decnergized, as by opening the switch 10, the magnetic flux in the magnetic circuit of the electro-magnet falls greatly in value, but does not fail to zero, for, as well understood, there is some of the magnetism that remains and is known as residual or remanent magnetism which, with an armature in magnetic contact with the poles, would ordinarily be sutlicient to hold the armature against the poles and tail to cause it with certainty to move away from them. When the electro-magnet has been deenergized as described the permanent magnet 11 by its magnetonnotive-force, exerted always-in the same direction, causes a flux through the magnetic circuit of the electromagnetQthe air gap or other reluctance (i preventing all but an inconsequential part of the flux to pass through the cores 3 and it and the armature T. The direction of this flux is opposite to that produced by the electro-magnet when energized, and accordingly the magneto-motive-force oi the permanent magnet reduces, or completely elimi nates the residual magnetism in the magnetic circuit of the electro-magnet, with the result that there is 110 flux between the poles N, S and the armature 7, whereupon the armature 7 falls away from the poles N, S. Or the magnetoanotive-fmrce of the permanent magnet 11 may not only cause the reduction of residual magnetic flux between the poles N, S and'the armature 7 to zero, butmay actually set up a flux in reverse direction. Since in such case the flux passes through zero value the armature 7 will fall away as described. The armature movement may be used to control a circuit or to cause or control actuation of any device. Assuming the permanent magnet 11 absent, upon energization of the electro-magnet by closure of switch 10 there will be generated in the coil 12, because of a change in magnetic flux el'nloraced thereby, an impulse of current which will make itself manifest in the instrument 13 by causing a deflection of its movable element. And upon openingthe switch 10, to deenergize the elect-ro-magnet, there willagain be produced in the coil 12 an impulse, but in opposite direction, which will again manifest itself by deflection of the instrument 13. But due to the remanent or residual magnetism the armature 7 will remain in the position illustrated in contact with the poles N, S. If now the permanent magnet 11 bereturned to the position shown, with its poles where indicated, the residual magnetism will be reduced, as before described, and this reduction. of magnetism will be manifested by another impulse in the coil 12 which will cause a deflection of the instrument '13 in the same direction as when the electro-magnet was deenergized,

menace for in both cases the" change in the-magnetic flux is in direction toward diminishing the flux.

In Fig. '2 a solenoid winding H is con nected in circuit with the source of current 9 and switch 10; if desired a current indicating or measuring instrument 15 may also be included in this circuit. \Vithin the solenoid coil 1 L is its core 16 of soft iron or other suitable magnetizable material and also a stationary core member 17 which may be recessed to receive the upper end of the core 16, in the case illustrated the recess and core being conical in shape in order that the magnetic reluctance between the members 16 and 17 may be reduced. or the switch 10 the solenoid is energized and the core 16 attracted to and held in magnetic contact with the second core member 17. Attached to or in magnetic contact with the upper end of the core 17 is one pole, as s, a south pole, of the permanentmagnet 18 whose north pole at is presented to the lower end of the core 16, but separated therefrom by an air gap (lr other reluctance producing neans. Under these circumstances the direction of the current through the solenoid winding la is such that its magnetosmotiveforce exceeds and acts in opposite direction to that of the permanent magnet 14. Were it not for the'presence of the permanent magnetlS in the relation indicated upon opening the switch lOto deenergize' the coil 1%, the core 16 would stick or adhere in magnetic contactto the core 17, due to the residual magnetism effect. But the permanent magnet 18, by its magneto-motive-force, now sets up in opposition to the relatively weaker residual magneto-motive-force a flux in opposite direction through the cores l6 and 17, reducing the residual magnetism to zero, whereupon the core 16 will drop. 7

In Fig. 3' the coils or windings 19 and 20 of the electro-magnet are connected in circuit with the source of current 9, switch 10, and if desired an instrument 15. The electro-magnet cores 21 and 22, of soft iron, or other suitable magnetizable material, are joined by the back armature or yoke 23, which may have a gap and reluctance adjusting means as shown with yoke 5 in Fig. l. The poles of the cores Ql'and 22, have depressions, as for example portions of the surface of a sphere, into which may fit in magnetic contact with the poles the spherical armature 24:. A permanent magnet 25 has its poles attached to the electro-magnet poles, as by screws 26. 'When the switch 10 is closed the electro-magnet will be energized and attract and hold thearmature 24 Upon closure in magnetic contact withthe electro-magnet poles, of which the left hand one may be associated with the south pole S, while the south pole s of the permanent magnet is associated with thenorth pole LT. 1f now the switch 10 be opened, the electro1nagnet will be deenergized, and the residual magnetism,

which would otherwise retain the armature 24in the position indicated in magnetic contact with the poles N, S, is reduced to zero by the permanent magnet 25, whereupon the armature 24 will drop. And even when armature 24 is of hard steel or other material which will become permanently magnetized when the electro-magnet/ is ener- -giz'ed, it will drop from the poles of deenergized an auxiliary magneto-motiveforce, such as that of a permanent magnet, and which has not been overcome or reversed by energization of the electroniagnet, comes into play and reduces the residual magnetism of the electro-magnet which would otherwise hold the armature in contact with the electro-magnet poles, such reduction of the residual magnetism -or its elimination allowing the armature to drop away, as in the case of an ordinary electromagnet where an air gap or non-magnetic material intervenes between the armature and the electro-magnet poles.

What I claim is:

1. The combination with an electromagnet, of an armature therefor normally held thereby in magnetic contact with a pole thereof in opposition to a force continuously exerted on said armature, and an opposing source of magneto-motive-force operative while said electromagnet is energized and associated with the magnetic circuit of said electr0-magnet for reducing the residual magnetism of said electro-magnet when deenerg'ized, whereby said armature is removed by said force before sa1d opposing source reestablishes substantial flux.

2. The combination with an electro-magnet, of an armature therefor normally held thereby in contact with a pole thereof in opposition to a force continuously exerted on said armature, and an opposing source of magneto-motive-force operative while said electro-magnet is energized and associated with the magnetic circuit of said electromagnet reducing the flux through said pole and armature when said electro-magnet is deenergized, whereby said armature is removed by said force before said opposing source reestablishes substantial fiux, the magnetic circuit of least reluctance of said auxiliary source of magneto-motive-force being through a pole and the armature of said electromagnet. v

3. The combination with an electro-magnet, of an armature therefor normally held thereby in contact with a pole thereof inopposition to a force continuously exertcd on said armature, means producing magnetic reluctance in the magnetic circuit of said electro-magnet, an opposing source of magneto-motive-force operative while said electro-magnet is energized and associated with the magnetic circuit of said electromagnet, and a magnetic circuit for said aux iliary source including said armature and a pole of said electro-magnet and excluding said magnetic reluctance producing means, said opposing source of magneto-motiveforce reducing the fiux through said pole and armature upon deenergization of said electro-magnet, whereby said armature is re moved by said force before said source reestablishes substantial flux.

4E. The combination with an electro-mag net, of an armature therefor normally held thereby in contact with a pole thereof in opposition to a force continuously exerted on said armature, and a permanent magnet associated with the, magnetic circuit of said electro-magnet and having its poles so disposed with respect thereto as to reduce the residual magnetism of said electro-magnet when deenergized'.

The combination with an electro-magnet having a pair of cores and a yoke therefor, of an armature adapted to be held by said electro-magnet when energized in magnetic contact with the polesthereof, means introducing magnetic reluctance .into said yoke, and a permanent magnet associated with the magnetic circuit of said electromagnet for reducing the residual magnetism thereof when deenergized, whereby said armature is removed by said force before said permanent magnet restablishes substantial flux.

'6. The combination with an electro-magnet having a pair of cores and a yoke therefor. of an armature normally held by said electro-magnet when energized 1n contact with a pole thereof in opposition to a force continuously exerted on said armature, an

air gap in said yoke, and a permanent magnet having its poles applied to opposite sides of said air gap. means for adjusting the reluctance of said air gap. said permanent magnet opposing said electro-magnet. whereby when said electro-magnet is deenergized said armature is removed bysaid force before said permanent-magnet reestablishes substantial flux.

7. The combination with an electro-magmeem'a not having a pair of cores and a yoke tl1eretor an air gap in said yoke, and axpermanent magnet opposing said eleotroanagnet having its poles applied to the magnetic circnit of said eleotr0'1nagn.et on opposite eides of said air gap.

8. The combination with an electro-inagnet having a pair of cores and a yoke therefor, an air gap in said yoke, a permanent nagnetopposing said electroanagnet having ts: poles applied to the magnetcircuit of.

said electro-rnagnet on opposite sides of said air gap, and means fol-adjusting the reluctance of said air gap.

9. The combination with an electro-niagnet, of an armature therefor normally held thereby in contact With a pole thereof in opposition to a force continuously exerted on said ai'n'iature, and a permanent magnet as soeiated with the magnetic circuit of said electi'o-magnet and opposing said electroinagnet when said electroanagnet is energized, whereby when said electi'o-lnagnet is deiinei'g'ized' said permanent magnet ire-- duces the residual magnetism of said electro-i'nag'net and said armature removed by said force before s id pennanent n'mg'net reestahlislies tlnx'snh' ient to hold said fil'lllil tare against said force.

In testimony whereof I hate hereunto aflixed my signature in the presence of the two subscribing" Witnesses.

GEORGE P. FINNIGAN.

ll itnesses N. B. EVANS, A. S. llL-XRSH. 

